Modern warfare and law enforcement are characterized by an increasing need for up-to-date situational awareness. To track down, or to protect against, criminals, paramilitary forces or terrorists, law enforcement personnel and soldiers often have an immediate need for information about what is around the next corner or over the hill.
Hostile forces frequently hide themselves from view or exploit the local terrain to gain tactical advantage or escape from pursuers. In the presence of hostile forces, a simple brick wall, barbed wire fence, a body of water, buildings or even a large open area can be an insurmountable obstacle when time is of the essence and tactical resources are unavailable. An active or undetected threat can make the situation dangerous.
Visible indications, noises or predictable actions can reveal friendly forces and put them at risk. Stealth and surprise, however, are important elements that can give a tactical advantage. An UAV is an aircraft with no pilot on board (also referred to herein as NUAV, where N is an abbreviation for Nano). UAVs can be remotely controlled (e.g. flown by a pilot/operator at a remote ground control station using a controller) or it can fly autonomously based on pre-programmed flight plans or more complex dynamic automation systems. An UAV may also be referred to as a drone. UAVs equipped with video cameras and positioning devices transmit live pictures and positioning information to the operator of the UAV and allows their operator to perform surveillance tasks and gather information from a safe position without exposing themselves.
An UAV may be operated and controlled using a remote control. Traditionally an UAV is operated by controlling such as e.g. a joystick. In addition to a joystick, the remote control configured to operate and control the UAV is usually also supplemented with a Graphical User Interface (GUI). A GUI may be a flight display providing e.g. different dynamic navigation information like speed, direction, waypoints etc.
All aircrafts need information about their local wind field to perform navigation—this includes UAVs. Smaller UAVs are more susceptible to atmospheric influences than larger UAVs or manned aircrafts and, therefore, require some method of identifying the current local wind field. In many instances, for these aircrafts, knowing the wind field will not aid an autopilot function in order to navigate the aircraft, but rather allow the aircraft to be positioned in a more advantageous orientation with respect to the wind.
Determination of the local wind field is most commonly achieved through the use of direct airspeed and ground speed measurements. The aircraft obtains information about its ground speed by using a combination of its GPS and inertial sensors. The aircraft obtains information about its direct airspeed by using a pilot (dynamic air pressure) probe. GPS sensor modules have become, in recent years, small and accurate enough to be carried in almost all aircrafts—this, however, does not apply to airspeed sensors.
The problem of being able to navigate the aircraft by using a measurement of the airspeed of an aircraft in one or more directions does usually not become an issue for most aircraft designers. It is simple to use a number of pressure sensors to measure airspeed on larger aircraft. This extends down to what is typically thought of as very small aircrafts, including aircrafts of only 100 g. Nano Unmanned Aerial Vehicles, however, are an order of magnitude smaller than this—approximately 15 g. Extending into this region necessitates that some cuts to system components of the aircraft are made—often the first to go is the airspeed sensors. This eliminates the possibility navigating the aircraft by using a direct measurement of the aircraft's airspeed.
If a small aircraft does not navigate by using a direct measurement of its airspeed it is difficult to use a measure the local wind field with any level of certainty. The problem of navigating the aircraft by using a calculation of the wind field from a known ground speed and airspeed is a known, solved problem.